The Allen Paradox is the observation that, in aquatic communities, there is insufficient prey production to support predator growth. An assessment of the literature reveals that this paradox remains apparent in one of every four studies. Here, a novel explanation for this paradox is proposed: predators that feed in a spatially-heterogeneous-prey environment (SHPE) may experience a greater net energy gain than in a corresponding uniform-prey environment (UPE), meaning that predators may require less food than has been traditionally perceived. A model was developed to simulate a predator’s energy gain while feeding in a SHPE rather than a UPE. According to the simulation, a greater net energy gain in a SHPE than a UPE is possible, but only under certain conditions. Since prey can be utilized more efficiently in a SHPE, a given amount of prey production can supply more predator growth, which can have positive implications in fish stocking.

The Allen Paradox is the observation that, in aquatic communities, there is insufficient prey production to support predator growth. An assessment of the literature reveals that this paradox remains apparent in one of every four studies. Here, a novel explanation for this paradox is proposed: predators that feed in a spatially-heterogeneous-prey environment (SHPE) may experience a greater net energy gain than in a corresponding uniform-prey environment (UPE), meaning that predators may require less food than has been traditionally perceived. A model was developed to simulate a predator’s energy gain while feeding in a SHPE rather than a UPE. According to the simulation, a greater net energy gain in a SHPE than a UPE is possible, but only under certain conditions. Since prey can be utilized more efficiently in a SHPE, a given amount of prey production can supply more predator growth, which can have positive implications in fish stocking.

Doctor of Philosophy / Department of Geography / Melinda Daniels / Geomorphic properties of streams are linked to ecosystem function through processes related to storage, transport, and other drivers regulating biogeochemical conditions. Disturbances altering the physical template of a stream are associated with cascading impacts on ecosystem function. However, few disturbances are studied at long time scales and so the legacy of such events and the implications for ecosystem structure and function are not well understood. This research investigates the role of historic tie-driving, a channel disturbance legacy, in shaping present-day stream channel conditions in the Rocky Mountain region and the associated implications for organic matter dynamics. Using a combination of geomorphic and riparian surveys, organic matter and vegetation sampling, and modeling, I show that components of mountain stream ecosystems have recovered from tie-driving at varying rates. First, I addressed how tie-driving has altered channel morphology and wood loading. Tie-driven streams are narrower, shallower, less rough, and have less wood than non-driven reference reaches. In a second study, I focused on differences in carbon storage within the stream and riparian area between tie-driven and non-driven streams. Carbon stored on the landscape represents a long-term component of the terrestrial carbon cycle and some, but not all, components have been impacted by tie-driving. Large instream wood, coarse downed wood, and fine downed wood were identified as carbon storage components that were significantly smaller in tie-driven stream-riparian corridors. Finally, I modeled whole stream ecosystem metabolism and tested whether abiotic drivers influenced variations in rates of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem productivity (NEP). Results from this work suggest that rates of GPP were significantly different between tie-driven and non-driven streams and were partially explained by variations in light related to canopy structure. However, variations in ER and NEP were not significantly different between tie-driven and non-driven sites. Taken as a whole, this work shows that ecosystems bear the imprint of historic disturbances but individual ecosystem components recover at differing rates. Additionally, integrating stream hydro-geomorphic and ecological dynamics is an effective approach to understanding the impact of channel disturbances in shaping ecosystem function at a variety of spatial and temporal scales.

Master of Science / Department of Biology / Craig Paukert / The zebra mussel is an invasive bivalve that was first confirmed in Kansas in 2003, and has decreased zooplankton abundance and altered the aquatic community in other areas where it has invaded. However, little is known about its effects on the aquatic communities of warm-water Great Plains reservoirs. We analyzed zooplankton, benthic macroinvertebrate, and juvenile and small-bodied fish abundance in the littoral zone of an Eastern Kansas reservoir with an established zebra mussel population (El Dorado Reservoir) and a control reservoir without zebra mussels (Melvern Reservoir) for two years pre-zebra mussel invasion (2001-2002) and two years post-invasion (2008-2009). We found no difference in littoral zooplankton abundance between reservoirs across time, but abundance of some macroinvertebrate taxa increased, and abundance of juvenile Lepomis spp. and red shiners decreased in the littoral zone of El Dorado Reservoir in August of the post-zebra mussel invasion period in comparison to the control reservoir. We also analyzed abundance and condition of six adult reservoir fishes in El Dorado Reservoir and three control reservoirs in Eastern Kansas for ten years pre-zebra mussel invasion (1993-2002) and five years post-invasion (2004-2008). Adult white crappie abundance remained constant in El Dorado Reservoir but decreased in the control reservoirs during the post-zebra mussel invasion period, and condition of adult bluegill, white bass, and white crappie decreased in El Dorado Reservoir in the post-zebra mussel invasion period compared to the control reservoirs. Our findings suggest that zebra mussel invasion in El Dorado Reservoir may have affected some benthic macroinvertebrates, juvenile and small-bodied fishes, and adult fishes. We did not find evidence that zebra mussels have had substantial effects on the zooplankton community of El Dorado Reservoir. However, July-August zebra mussel veliger densities in El Dorado Reservoir averaged less than 12 veligers/L in four of the six post-zebra mussel invasion years. Additional research and long-term monitoring of zooplankton, macroinvertebrates, and fishes will be necessary to determine the full effects of zebra mussels on the aquatic communities of warm-water reservoirs throughout North America.

Master of Science / Department of Biology / Craig Paukert / In-stream dredging is a common practice in rivers worldwide that can affect fish and fish habitat. We investigated the magnitude of these alterations and their influence on the fish community of the Kansas River, a large sand bed river. Fishes were collected monthly from June 2010 to June 2011 in Edwardsville and Lawrence, KS from 12, 1-km reaches (three actively dredged, two historically dredged that have not been dredged in at least one month, and seven control reaches) with bottom trawls, seines, and electrofishing. Water depths and velocities were measured with an acoustic doppler current profiler and interpolated in ArcGIS at all 12 reaches. Actively dredged reaches had proportionally more deep water habitat (> 3 m) and lower velocity (< 0.15 m/s) near the river bed than control reaches (P < 0.01 and P = 0.04, respectively). However, the mean proportion of shallow water habitat (< 0.5 m), high velocities near the river bed (> 0.30 m/s), low velocity habitat (< 0.25 m/s), and high velocity habitat (> 0.75 m/s) were similar among all reach types (Ps > 0.05). A canonical correspondence analysis was used to characterize relationships among habitat variables, reach types (actively dredged, historically dredged, and control), and catch per unit effort (CPUE) of fishes in the Kansas River. Mean velocity and depth explained a significant amount of variation in species CPUE; however, reach type was not a significant factor for any of the gear types for any season. Our results show that dredging in Great Plains Rivers can increase depths, but alterations to fish community structure was not evident, likely because many of these fishes are adapted to a range of habitat conditions and are highly mobile.

Estimating the risk associated with species and pathogen movements involves considerable uncertainty. One key uncertainty concerns the extent and frequency of human-mediated species and pathogen movements relative to the distribution of recipient ecosystems. Baitfish use in Ontario, Canada is one of many pathways with the potential to introduce and spread biota to beyond their current geographic range. To determine the biological risk associated with baitfish use, models were used to estimate the probability of species occurrences throughout pathway levels, from the commercial harvest level, to retail tank and angler purchases, to movement and release by the end-user (i.e., the angler). Vector activity, as the primary contributor of species movements and introductions associated with this pathway, was modeled within a spatial interaction framework that incorporated landscape structure (e.g., the distribution of angling populations, lake size and sportfish richness, and their physical separation via least-cost routing of transportation networks) to predict the extent of movement. Agent-based models of vector activity were used to relate vector movements to region-specific probability thresholds of risk activity. Model outputs were used to estimate the movement and introduction of species and pathogens to lake ecosystems resulting from a variety of infection scenarios. Species results identified a pronounced reduction in the probability of non-target species occurrences throughout pathway levels. However, the occurrence of biological invaders and other non-target fishes at retail levels implied incidental bycatch throughout the pathway. Relatively short, frequent vector movements associated with incidentally purchased species were very likely, yet would not contribute to species range expansions due to the homogeneity of biological communities at those levels. However, rarer, yet considerably lengthier, vector movements associated with key species and pathogens implied the potential for low-probability, long-distance species and pathogen movements resulting from human activities.

Estimating the risk associated with species and pathogen movements involves considerable uncertainty. One key uncertainty concerns the extent and frequency of human-mediated species and pathogen movements relative to the distribution of recipient ecosystems. Baitfish use in Ontario, Canada is one of many pathways with the potential to introduce and spread biota to beyond their current geographic range. To determine the biological risk associated with baitfish use, models were used to estimate the probability of species occurrences throughout pathway levels, from the commercial harvest level, to retail tank and angler purchases, to movement and release by the end-user (i.e., the angler). Vector activity, as the primary contributor of species movements and introductions associated with this pathway, was modeled within a spatial interaction framework that incorporated landscape structure (e.g., the distribution of angling populations, lake size and sportfish richness, and their physical separation via least-cost routing of transportation networks) to predict the extent of movement. Agent-based models of vector activity were used to relate vector movements to region-specific probability thresholds of risk activity. Model outputs were used to estimate the movement and introduction of species and pathogens to lake ecosystems resulting from a variety of infection scenarios. Species results identified a pronounced reduction in the probability of non-target species occurrences throughout pathway levels. However, the occurrence of biological invaders and other non-target fishes at retail levels implied incidental bycatch throughout the pathway. Relatively short, frequent vector movements associated with incidentally purchased species were very likely, yet would not contribute to species range expansions due to the homogeneity of biological communities at those levels. However, rarer, yet considerably lengthier, vector movements associated with key species and pathogens implied the potential for low-probability, long-distance species and pathogen movements resulting from human activities.

Doctor of Philosophy / Department of Biology / Keith B. Gido / A large scale habitat manipulation was conducted to assess the effects of establishing an emergent macrophyte, American water willow Justicia americana, on littoral reservoir communities. Coves in three large (>1,800 ha) Kansas impoundments were chosen and half planted with water willow. Sampling was conducted during the summer from 2001 to 2004. I found that water willow coves had more complex habitat as well as higher abundance and diversity of fishes, macroinvertebrates, and zooplankton than control coves. However, strong temporal variation in water levels influenced the amount of inundated water willow available in these systems. The effects of water willow on density, growth, condition, and diet of age-0 largemouth bass Micropterus salmoides were assessed. Significantly higher densities of age-0 largemouth bass were found in water willow coves, but growth, condition, and diet did not differ between water willow and control coves. Therefore, water willow was able to support higher abundances of age-0 largemouth bass than control coves without affecting growth, condition, or diet. Characteristics of age-0 largemouth bass from the water willow coves were compared to those from two small impoundments (<80 ha) with abundant macrophyte and healthy largemouth bass populations. Small impoundments had higher densities of age-0 largemouth bass than water willow coves in the three large impoundments, but individuals on average also had lower growth, condition, and fewer fish in their diet. Thus, largemouth bass populations in small impoundments may be more regulated by density dependent factors than populations in large impoundments. Overall, water willow is beneficial to littoral areas, supporting an increase in both abundance and diversity of assemblages. Finally, I used a field experiment to test the inundation and desiccation tolerance of water willow for different depths and durations. Water willow was susceptible to inundation, but resistant to desiccation. My findings provide information that can be used to select candidate reservoirs for water willow establishment based on expected water-level fluctuations.

Master of Science / Department of Statistics / John E. Boyer Jr / The purpose of this study is to evaluate the effectiveness of the methods used for allocating disaster funds to assist commercial fishery participants as a result of Hurricanes Katrina and Rita of 2005 and to examine alternative methods to aid in determining an efficient criterion for allocating public funds for fisheries assistance. The trip ticket data managed by the Louisiana Department of Wildlife and Fisheries were used and analyzed using a cluster analysis. Results from the clustering procedures show that commercial fishermen consist of seven clusters, while wholesale/retail seafood dealers consist of six clusters. The three tiers into which commercial fishermen were originally classified can be extended to at least eleven (11) clusters, made up of three (3) clusters in tier 1 and an equal number of clusters (4) clusters in tier 2 and tier 3. Similarly, the original three tiers of wholesale/retail seafood dealers can be reclassified into at least nine (9) clusters with two clusters in tier 1, four (4) clusters in tier 2 and three (3) clusters in tier 3. As a result of the clustering reclassifications, alternative compensation plans were developed for the commercial fishermen and wholesale/retail seafood dealers. These alternative compensation plans suggest a reallocation of disaster assistance funds among individual groups of fishermen and among individual groups of dealers. We finally recommend that alternative classification methods should always be considered in order to select the most efficient criterion for allocating public funds in the future.

Doctor of Philosophy / Department of Biology / Craig Paukert / River discharge influences fish and invertebrate communities and understanding how hydrologic variables contribute to fish and invertebrate composition can provide information for restoration and management. This study examines the relationship between several flow regime metrics that may influence fish and invertebrate community structure in large river systems such as the Kansas River. First, I examined how hydrology influences macroinvertebrate (drifting and benthic) density and fish communities before, during, and after flooding in both main and secondary channels. I found that drifting invertebrate density increased during flooding potentially providing increased prey opportunities for fishes. I also found that fluvial dependent and generalist fish species use inundated habitats more than fluvial specialists. My results suggest that the flux of water into inundated habitats supports a unique subset of invertebrate and fish communities of the main channel. Next, I examined the importance of lateral connectivity on fish and invertebrate composition by examining differences in seasonally and permanently inundated secondary channels in relation to main channel reaches. I found that drifting and benthic invertebrate assemblages and fish assemblages differed between seasonally inundated and permanently connected secondary channels. These results suggest that maintenance of diverse secondary channel connections is useful in preserving native biota in the Kansas River. Finally, I tested if hydrologic variables influenced recruitment of four native Kansas River fishes. I found that recruitment for two of the four fish species (flathead catfish, Pylodictis olivaris, and shovelnose sturgeon, Scaphirhynchus platorynchus) increased in high flow years. These results indicate that a natural and variable flow regime may be important for maintaining fish community structure in the Kansas River. The results of this study have implications for management strategies that include the use of high flows to provide a pulse of insect prey to the main channel for fishes, restoration of natural high and low flow variability as important to fish recruitment, and diversity in secondary channel connectivity (seasonal and permanently connected) that promotes unique fish and invertebrate communities.